As reported by Bill McGinnis, Omniflight Base Manager (now Air Methods) in Sioux Falls, South Dakota
There are companies putting up "Met Towers" in the Upper Midwest and other parts of the country. These towers are 198 feet tall, not painted, and very fast to erect. They have only 4 guide wires on the tower. They are used to gather wind data for the feasibility of erecting large Wind Turbines for the production of electricity. These towers stay up for a few days to a year to gather data. They can be put up in just a few hours. They are not marked and do not have lights on them. The FAA pointed out that they had noted three of these towers along about a 50 mile stretch of a South Dakota highway. As obstruction lighting is not required for towers less than 200', some FAA POI's have suggested a push to have the towers painted to make them more visible. These towers could be a real hazard at a scene or even near a hospital.